Buffer spring device for drilling machines



March 9, 1948.

` A. HOSSFELD l BUFFER SPRING DEVICE FOR DRILLING MACHINESI Filed Jan.19, 1944 Y. UNITED Vsrrrrs Patented Mar. 9, 1 948 ,A

BUFFER SPRING DEVICE FOR .DRILLING MACHINES Albert nossfeia, Winona,Mining The Merchants National BankV of Winona, administratorlof saidAlbert Hossfeld, deceased Y Application January 19, 1944, Serial No.519,071

7 Claims. (Cl. 267-1) My present invention relates to improvements inbuffer spring devices for use vin drilling machines 'of the typedisclosed and broadly claimed in 'my'United States Letters Patent No.1,388,668, issued November 22, 1932. F

The drill 'in the type of drilling machine above referred to .is mountedfon a reciprocating lcarriage for endwise reciprocating movement that isindependent ofthe reciprocating 'movement of the carriage. A pair ofcompression springs is provided for reciprocating the drill at a greaterspeed than that of the carriage. One of these springs :acts as apropelling spring for the drill to produce its operative :stroke and theother oi said springs acts Vas a buffer spring for starting thecomparatively heavy drill on its upward stroke and accelerate itsmovement. The propelling spring is placed `under tension by the drillduring its return stroke and drives said drill by its expanding movementa't high velocity during its operative stroke. The buffer spring isplaced under tension during the rst part of the return stroke and itsexpanding movement Yduring the latter part of the stroke retracts thedrill at high velocity. VDue to the high velocity at which the drill isoperated, the life of ordinary propelling and buiier springs isrelatively short.

The objection to the ordinary propelling spring was `overcome bysubstituting therefor a novel spring device disclosed and broadlyclaimed in my United States Letters Patent No. 1,930,098, issued October10, 1933, and entitled 4Spring device for drilling machines.

It is well known that it is not the normal compression and expansionY ofa compression spring that shortens its life, but the stretch thereofthat takes place beyond the normal expansion of a spring expanding athigh velocity.

The objects of this invention are: first, to provide positive means forpreventing a buffer spring from stretching beyond its normal expandinglimit; second, to provide a bu-ier spring assembly that will not loosenup or come apart under the terrific .strain placed thereon bythe highvelocity of thedrill andv its reciprocatory travel; third, to provide abuier spring assembly that can be quickly and easily placed in .itsoperative position in a drilling machine while in the eld; and fourth,to `provide a .buier spring assembly in which the several parts .thereofcan be put together without 'the use of tools.

To the above end, generally stated, the invention consists of the novel.devices and combination .of devices hereinafter described and `definedin the claims.

In the accompanying drawing which illustrates the invention, likecharacters' indicates like parts throughout the several views.

Referring to the drawing:

Fig. '1 ris a fragmentary perspective view of a drilling machine havingthe presentvinvention embodied therein;

Fig. 2 is an enlarged view ofthe buffer spring assembly in centralVlongitudinal section and also showing, fragmentari'ly, vassociatedparts:ofthe drilling machine;

Fig.. 3 is a view corresponding to Fig. 2, but showing only the lowervportion of the `buffer spring assembly and the lowercross-head of thedrilling machine; f

Fig.. 2l is a bottom-'plan view of the buffer spring assembly, as shownin Fig. 3;

Fig. 5 is a View' in horizontal section taken on the line 55 of Fig. 3';y l

Fig. Gis a view corresponding to'Fig. .5, with the exception'th'at the.collar quadrants are separated from the sleeve member;

vFig.. 7 is a View partly in elevation with the sleeve .member and thecollar quadrants separated, as shown in Fig. '6; and

Fig. `8 is a view showing one of the rubber bands used in holding thecollar quadrants applied to the sleeve.

Of the parts of the drilling :machine shown, it is important'tonote thevdrill 9, `the main frame it, the carriage H, the tilting frame I2, .the.connecting rods y:41% Vfor reciprocating the carriage H on Vthe framele., the drill propelling spring device ifi, the buier spring assemblyl5, which is the-subject matter of the vpresent invention, and

therfrictlon grip 1E; The drill A5l includes a bodyA il inthe form of `along round steel rod and a cutter i8 on one end cisaid body. This drille is :mounted on the vcarriage H for :compound reciprocating and rotarymovements.

The tilting frameflZ'includes a pair yof laterally spaced guide postsisland a pair of cross-tie plates 2Q rigidly rsecured thereto and heldlater ally spaced thereby, the one from the other. A striker plateZl forthe grip t6 rests on the crosstie plates 2e and is secured thereto.

The carriage VIl includes ran .upper cross-head 22 slidably mounted onthe posts t9, a lower cross-head ris that `affords a spring base and apair of rods 24 which hold said lower cross-head suspended from theupper cross-head 22 between the cross-tie plates 20. axially throughthel spring rdevice M and the buffer spring device l5. vSaid springdevice lll, at its outer end, is Vattached'to -a Vrotatable `bear- The`drill 9 extends 3 ing 25 on the cross-head 22 and is oscillated duringreciprocatory movement of the carriage II by connections 26 from saidbearing to the tilting frame l2.

Obviously, the bearing 25 and hence the upper cross-head 22 afford abase of resistance for the spring device I4 and the spring of the buerspring device I5 rests on the lower cross-head 23 which aords a base ofresistance therefor. The friction grip I6 is mounted on the drill bodyI1 between the spring device I4 and the buffer spring assembly I5.Normally the cutter I8 of the drill 9 rests on the material beingdrilled, the friction grip IB `iust contacting the striker plate 2| andthe fully expanded buffer spring assembly I5 just contacting thefriction grip I6.

Operation of the drilling machine -thus far described may be brieflydescribed as follows, to wit:

As the carriage II starts on its upward travel, the buffer springassembly I5 is compressed against the friction grip I6 and absorbs theshock of starting the comparatively heavy drill 9 on its upward stroke.As the carriage gradually slows down and comes to a stop at the upperend of its travel the compressed buffer spring assembly I5 expands thusretracting the drill 9 to a much higher speed than that attained by thecarriage II at any point of its travel, During this upward travel of thedrill 9, the grip I6 engages the propelling spring device I4',compresses the same under powerful tension and at which time thepropelling spring device I4 absorbs the shock of the drill 9 and bringsthe same to a stop at the limit of the upward travel of the carriage II. Downward movement of the carriage I I gives the drill 9 a powerfuldownward throw which is accelerated by the expansion of the compressedypropelling spring device I4 and causes the drill 9 to attain a highvelocity as it travels to its work. At or practically at the end of thedownward stroke of the drill 8, the grip I6 is brought to a stop by itsengagement with the striker plate 29 and as the drill 9 advances intothe work, it drives itself through the grip I5 by the force of itsmomentum. The feeding of the drill 9 through the grip I6 takes place ata series of almost imperceptible steps of movement.

For the purpose .of this case, it is not thought necessary to describein detail the rotary movement imparted to the drill 9 except to statethat during the downward travel of the carriage II, and while the gripI6 is in engagement with the spring device I4, said spring device isgiven a turning movement about its longitudinal axis by the connections26 which imparts a like movement to said drill by frictional engagementbetween the spring device I4 and the grip I6.

Referring now to the buffer spring assembly I5, in detail, the sameincludes a long sleeve 21 through which the drill 9 loosely extends.This sleeve 21 has on its upper end a spring seat 25 in the form of anannular shoulder that surrounds said sleeve. Encircling the sleeve 21 isa coiled spring 29. The lower end portion of the sleeve 21 has formedthereon a multiplicity of independent serrations 30. These serrations 30lie in parallel planes and each thereof is endless. A serrated collar 3|is applied to the serrated end portion of the sleeve 21 and comprisesseparate quadrants. This collar 3| is internally serrated at 32 to matchthe serrations 30. An annular external channel 33 is formed in thecollar 3l. The collar 3| is yieldingly held on the sleeve 21 with itsserrations 32 interlocked with the serra- 4 tions 39 of said sleeve by aplurality of rubber bands 3, one of which is shown in Fig. 8. Eachrubber band 3d is applied around the collar 3| in its channel 33 andstretched so that it is under strain to draw the collar quadrants ontothe sleeve 21. It is important to note that the ends of the collarquadrants are spaced apart so as not to interfere with the clamping ofsaid quadrants onto the sleeve 21.

rlhe sleeve 21 extends axially through a hole in the lower cross-head 23with the spring 29 between the lower cross-head 23 and the spring seat29 and the collar 3| is under the lower crosshead 23. In the under sideof the cross-head 23 is a seat 35 for the collar 3|. This seat 35 andthe upper end portion of the collar 3| have beveled or ball and socketengagement, the one with the-other. The adjustment of the collar 3| onthe sleeve 21 is such that when pressure is removed from the bufferspring assembly I5, the spring 29 is held under slight compression. At

the time the buffer spring assembly I5 engages the grip I3, which isduring the upward travel of the carriage ll, the spring 29 is compressedby the force of this engagement. The compression of the spring Z9 movesthe sleeve 21 endwise downwardly through the cross-head 23 and thecollar 3| out of the seat 35. When pressure is removed from the bufferspring assembly I5, the cornpressed spring 29 expands and returns thesleeve 21 and the collar 3| to their original positions. At the time thecollar 3| enters the seat 35, the beveled or ball and socket surfacesthereof center the collar 3l in the seat 35 and the sleeve 21 in thehole in the cross-head 23.

From the foregoing, it is evident that the spring 29 is positivelystopped from expanding beyond a predetermined point and this point isdetermined by the distance the spring seat 28 is positoned from thecross-head 23 and the nut 3|.

It has been found that by limiting the expanding movement of the spring29 to prevent stretch thereof beyond its normal length, the life of saidspring was materially increased.

The rubber bands Sil hold the collar 3| on the sleeve 21 so that thereis no lateral movement of said collar relative to the sleeve and saidcollar will not work up or down on the sleeve 21 under the action of thejars produced on the buffer spring assembly i 5 by its engagement withthe grip I6 and the alternate engagement of the collar 3| with thecross-head 23.

Toremove the collar 3| from the sleeve 21 it is only necessary to removethe rubber bands 34 from said collar and slightly compress the spring 29to relieve the inward wedging action of the beveled or ball shaped seat35 against the beveled or ball shaped end of said collar. In the absenceof rubber bands, a piece of string or other slightly elastic materialwrapped tightly around the collar 3| will serve as a tie and hold itsecurely to the sleeve 21.

It will be understood that the invention described is capable of variousmodications within the scope of the invention herein disclosed andclaimed.

What I claim is:

1. In a device of the class described, a structure having a spring base,means for reciprocating the structure at high speed, a sleeve extendingthrough the spring base for relative endwise movement, said sleevehaving at one end a spring seat and at its other end portion a pluralityof parallel serrations, a sectional serrated collar applied to theserrated end portion of the sleeve and having serrations matching theserrations on the sleeve, the sections of the serrated collar beingseparable by relative lateral movement, means holding the sectionalcollar contracted onto the sleeve, a spring compressed between thespring base and the spring seat and yieldingly holding the collar inengagement with the spring base, and a tool extending through the sleevefor relative reciprocation and which is thrown to its work by thereciprocating structure, said tool during movement to its work engagingthe sleeve, compressing the spring and moving the collar away from thespring base, the expansion of the spring returning the tool from itswork.

2. The structure dened in claim 1 in which the means holding thesectional serrated collar contracted onto the sleeve is a yieldingmeans.

3. The structure dened in claim 1 in which the means holding thesectional serrated collar contracted onto the sleeve is a stretchedrubber band applied around the collar.

4. The structure dened in claim 1 in which the serrated collar hastherein an annular channel, and in which the means holding the sectionalserrated collar contracted onto the sleeve is a stretched rubber band inthe channel.

5. In a spring device, a spring base, a sleeve extending through thespring base for endwise movement, said sleeve having at one end a springseat and at its other end portion parallel serrations, a sectionalserrated collar applied to the serrated end portion of the sleeve andhaving serrations that match the serrations on the sleeve, the sectionsof the serrated collar being separable by relative lateral movement,means holding the collar with its serrations interlocked with theserrations on the sleeve, and a spring compressed between the springbase and the spring seat, said spring base having a seat for the collar,the contacting surfaces between the collar and its seat convergingtoward the longitudinal axis of the sleeve.

6. In a spring device, a spring base, a sleeve extending through thespring base for endwise movement, said sleeve having at one end a springseat and at its other end portion parallel serrations, a sectionalserrated collar applied to the serrated end portion of the sleeve andhaving serrations that match the serrations on the sleeve, the sectionsof the serrated collar being separable by relative lateral movement,means holding the collar with its serrations interlocked with theserrations on the sleeve, andk a spring compressed between the springbase and the spring seat, said spring base and collar having ball andsocket engagement.

7. The structure defined in claim 1 in which the sleeve extends througha hole in the spring base with working clearance, said spring basehaving a seat for the collar, said seat and collar having contactingsurfaces that center the sleeve in the hole in the spring base each timethe sleeve is moved by the expanding spring.

ALBERT HOSSFELD.

Ymtrmmuciis CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 397,882 Westaway Feb. 12, 1889576,119 Hess Feb. 2, 1897 576,543 Burr Feb. 9, 1897 1,464,524 GilmourAug. 14, 1923 1,595,317 Scholey Aug.'10, 1926 1,887,963 Stafford Nov.15, 1932 1,930,098 Hossfeld Oct. 10, 1933 2,123,048 Hossfeld July 5,1938 2,210,811V Kelpsch Aug. 6, 1940 2,226,914 Sharon Dec. 31, 1940

